This application is based upon and claims benefit of priority of Japanese Patent Application No. Hei-11-276939 filed on Sep. 29, 1999, the content of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a compound heat exchanger having plural heat exchanger cores, and more particularly to a compound heat exchanger having a condenser core for cooling refrigerant in an air-conditioning system and a radiator core for cooling coolant of an internal combustion engine. The compound heat exchanger is suitably used in an automobile vehicle.
2. Description of Related Art
An example of a compound heat exchanger having a condenser core and a radiator core is disclosed in JP-U-4-15281. In this compound heat exchanger, the condenser core and the radiator core are connected into a single unit by an integrally formed member having a condenser header tank cap and a radiator header tank cap. The condenser header tank cap closes an open end of the condenser header tank connected to the condenser core, while the radiator header tank cap closes an open end of the radiator header tank connected to the radiator core.
In the conventional compound heat exchanger disclosed in the above publication, heat in the radiator header tank is transferred to the condenser header tank through the integrally formed member because both header tanks are connected by the integrally formed member. Therefore, the refrigerant in the condenser header tank is heated by the heat transferred from the radiator header tank, and thereby a heat radiation capacity of the condenser core decreases.
The present invention has been made in view of the above-mentioned problem, and an object of the present invention is to provide an improved compound heat exchanger in which the heat transfer between two header tanks is suppressed and a high heat radiation capacity is realized.
The compound heat exchanger includes a first heat exchanger such as a condenser for cooling refrigerant circulating in an air-conditioner and a second heat exchanger such as a radiator for cooling coolant in an internal combustion engine. The first and the second heat exchangers are overlapped on each other in an airflow direction of cooling air. Both heat exchangers have a similar structure, that is, each heat exchanger is composed of a core having plural tubes and fins and a pair of header tanks connected to both ends of the tubes. Both cores are connected to each other by a side plate disposed on the top of both cores, so that at least a top fin of one of the cores, preferably both top fins, contacts the side plate in heat conductive relation. Preferably, a pair of fins for both cores is formed as a unitary part, and each header tank is formed by connecting two separate elongate cup-shaped or L-shaped parts.
Upper openings of both header tanks are closed with respective tank caps that are connected to the side plate. After all the components, header tanks, cores, tank caps and the side plate are assembled together, the compound heat exchanger is connected into single unit by a brazing process. Since both tank caps are separate from each other, though they are connected to the common side plate, heat in one header tank is not directly transferred to the other header tank. For example, most heat in the radiator header tank is transferred to the side plate via its tank cap and is radiated from the side plate and the fin contacting the side plate. Accordingly, the radiation capacity is not much decreased by combining two heat exchangers.
Preferably, positioning walls and side walls are formed on the side plate to fix the tank caps at correct positions and thereby to prevent the header tanks from being positioned with slanted angles relative to the cores. The tank caps are inserted and held between the positioning and side walls of the side plate when assembled, and then the tank caps and the side plate are firmly connected by brazing.
Both tank caps may be made as a single part having cap portions and connecting portions, as long as two cap portions are separated from each other with a certain space therebetween. Alternatively, both tank caps may be formed integrally with the side plate, with cap portions being positioned separately form each other. Further, one of the tank caps may be formed integrally with the side plate, while the other one is separately made and connected to the side plate by brazing. Both tank caps may be integrated with a mounting bracket via connecting portions with cap portions being positioned separately from each other.
According to the present invention, the heat in one header tank is not directly transferred to the other header tank, and therefore a high radiation capacity in the combined heat exchanger is realized.
Other objects and features of the present invention will become more readily apparent from a better understanding of the preferred embodiments described below with reference to the following drawings.